摘要
通过对莱州湾凹陷区域构造地质背景、岩石学特征、沉积环境等分析,认为莱州湾凹陷南部地区古近系沙三下亚段的地层埋藏浅,广泛发育湖相碳酸盐岩与陆源碎屑岩的混合沉积,混合沉积特征主要为结构混合和互层混合。考虑到混积岩成分和成因的复杂性,本文在岩心、壁心观察、铸体薄片鉴定、荧光薄片鉴定和扫描电镜分析的基础上,对莱州湾凹陷南部地区混积岩样品进行了X-射线衍射分析和岩石有机质中碳氢氧元素分析,分析了碳酸盐岩和陆源碎屑岩混积的岩石学特征。结果显示:莱州湾凹陷南部地区浅层沙三下亚段混积岩中陆源碎屑平均含量为60.5%,碳酸盐矿物含量为28.2%,属于碳酸盐质陆源碎屑岩,混积岩主要为泥灰岩、灰质砂岩和砂质白云岩。其中,碎屑矿物主要以细-粉砂级石英为主,碳酸盐矿物主要为泥晶方解石;粘土矿物组合主要为伊蒙混层,其次为伊利石、高岭石和绿泥石;且三者呈均匀混合的特征。同时通过铸体薄片、扫描电镜和储层流体包裹体观察,综合分析成岩作用表明,埋藏浅的沙三下亚段混积岩储层主要经历了压实、压溶作用、溶蚀作用、胶结交代作用,其中胶结交代作用较强,而研究区压实、压溶作用对比渤海湾盆地大部分埋藏较深的古近系地层都弱,储集空间以原生粒间孔为主,其次为粒内溶蚀孔和微缝。压实、压溶作用弱和溶蚀作用强是研究区沙三下亚段储层物性好的主要原因。
The exploration of lithologic structural reservoirs in the southern part of the Laizhouwan sag is still in its infancy,and its research on petrological characteristics,sedimentary environment and accumulation characteris-tics is relatively weak.Based on the analysis of the tectonic geological background,petrological characteristics and sedimentary environment of the Laizhouwan sag,it is considered that the lower Paleozoic strata of the Paleogene in the southern part of the Laizhouwan sag are shallowly buried and widely mixed with lacustrine carbonate and terrigenous clastic rocks.The deposition and mixed deposition characteristics are mainly structural mixing and interbed mixing.Considering the complexity of the composition and genesis of the mixed rock,based on the core,wall core observation,casting thin section identification,fluorescent thin section identification and scanning elect-ron microscopy analysis,the mixed rock samples in the southern part of the Laizhouwan sag were X-Ray diffraction analysis and analysis of carbon and oxygen in rock organic matter analyzed the petrological character-ristics of the mixture of carbonate and terrigenous clastic rocks.The results show that the average content of terrigenous clastics is 60.5%,and the carbonate mineral content is 28.2%in the mixed rock of the lower Es 3 in the southern part of the Laizhouwan sag.It belongs to carbonate-based terrigenous clastic rocks,mainly gray matter.Mudstone,in which the detrital mineral is mainly fine-grained quartz;the carbonate mineral is mainly mud-calcite;the clay mineral combination is mainly disordered illite/smectite formation,followed by illite,kaolinite and chlorite;And the three are characterized by uniform mixing.At the same time,through the observation of casting thin sections,scanning electron microscopy and reservoir fluid inclusions,the comprehensive analysis of diagenesis shows that the mixed rock reservoirs in the lower Es 3 sub-segment mainly undergo compaction,pressolution,dissolution cementation and metasomatism.The cementation and metasomatism are strong,and the diagenesis in the study area is weak compared with most of the Paleogene in the Bohai Bay basin.The reservoir space is dominated by primary intergranular pores,followed by intragranular dissolution pores and micro-seams.The weak compaction and strong dissolution are the main reasons for the reservoir properties of the lower Es 3 in the study area.
作者
王梦琪
张强
谢俊
周亚伟
段雅君
杨旭东
孟子昂
WANG Meng-Qi;ZHANG Qiang;XIE Jun;ZHOU Ya-Wei;DUAN Ya-Jun;YANG Xu-Dong;MENG Zi-Ang(College of Earth Science and Engineering,Shandong University of Science and Technology,Qingdao 266590,China)
出处
《中国海洋大学学报（自然科学版）》
CAS
CSCD
北大核心
2020年第4期83-94,共12页
Periodical of Ocean University of China
基金
国家自然科学基金项目(51674156)资助。
